Merge pull request #778 from fartem/443_String_Compression

2024-11-21 v. 7.0.8: added "443. String Compression"

Author: fartem

README.md

@@ -573,3 +573,4 @@ Profile on LeetCode: [fartem](https://leetcode.com/fartem/).
 | 437. Path Sum III                                               | [Link](https://leetcode.com/problems/path-sum-iii/)                                               | [Link](./lib/medium/437_path_sum_iii.rb)                                               | [Link](./test/medium/test_437_path_sum_iii.rb)                                               |
 | 438. Find All Anagrams in a String                              | [Link](https://leetcode.com/problems/find-all-anagrams-in-a-string/)                              | [Link](./lib/medium/438_find_all_anagrams_in_a_string.rb)                              | [Link](./test/medium/test_438_find_all_anagrams_in_a_string.rb)                              |
 | 442. Find All Duplicates in an Array                            | [Link](https://leetcode.com/problems/find-all-duplicates-in-an-array/)                            | [Link](./lib/medium/442_find_all_duplicates_in_an_array.rb)                            | [Link](./test/medium/test_442_find_all_duplicates_in_an_array.rb)                            |
+| 443. String Compression                                         | [Link](https://leetcode.com/problems/string-compression/)                                         | [Link](./lib/medium/443_string_compression.rb)                                         | [Link](./test/medium/test_443_string_compression.rb)                                         |

leetcode-ruby.gemspec

@@ -5,7 +5,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '7.0.7'
+  s.version = '7.0.8'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'

lib/medium/443_string_compression.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# https://leetcode.com/problems/string-compression/
+# @param {Character[]} chars
+# @return {Integer}
+def compress(chars)
+  prev = chars[0]
+  prev_count = 0
+  chars_with_count = []
+  chars.each do |char|
+    if char == prev
+      prev_count += 1
+    else
+      chars_with_count << prev
+      prev_count.to_s.each_char { |c| chars_with_count << c } if prev_count > 1
+
+      prev = char
+      prev_count = 1
+    end
+  end
+
+  chars_with_count << prev
+  prev_count.to_s.each_char { |c| chars_with_count << c } if prev_count > 1
+
+  (0...chars_with_count.size).each { |i| chars[i] = chars_with_count[i] }
+
+  chars_with_count.size
+end

test/medium/test_443_string_compression.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+require_relative '../../lib/medium/443_string_compression'
+require 'minitest/autorun'
+
+class StringCompressionTest < ::Minitest::Test
+  def test_default_one
+    input = %w[a a b b c c c]
+
+    assert_equal(6, compress(input))
+    assert_equal(%w[a 2 b 2 c 3 c], input)
+  end
+
+  def test_default_two
+    input = ['a']
+
+    assert_equal(1, compress(input))
+    assert_equal(['a'], input)
+  end
+
+  def test_default_three
+    input = %w[a b b b b b b b b b b b b]
+
+    assert_equal(4, compress(input))
+    assert_equal(%w[a b 1 2 b b b b b b b b b], input)
+  end
+end